1.三元运算符

新手

let hungry = true;
let eat; 
if (hungry == true) {
       eat = 'yes'; 
} else {
       eat = 'no';
}

老手

let hungry = true;
let eat = hungry == true ? 'yes' : 'no';

2.数字转字符串/字符串转数字

新手

let num = 15; 
let s = num.toString(); // number to string
let n = Number(s); // string to number

老手

let num = 15;
let s = num + ""; // 数字转字符串
let n = +s; // 字符串转数字

3.填充数组

新手

for(let i=0; i < arraySize; i++){
  filledArray[i] {'hello' : 'goodbye'};
}

老手

let filledArray = new Array(arraysize).fill(null).map(()=> ({'hello' : 'goodbye'}));

4.对象的动态属性

新手

let dynamic = "value"; 
let user = {
     id: 1,
};
user[dynamic]: "other value"; 

老手

let dynamic = "value"; 
let user = {
    id: 1,
    [dynamic] = "other value"
};

5.删除重复项

新手

let array = [100, 23, 23, 23, 23, 67, 45]; 
let outputArray = [];
let flag = false; 
for (j = 0; < array.length; j++) {
   for (k = 0; k < outputArray.length; k++) {
      if (array[j] == outputArray[k]) {
         flag = true;
       }
    }
    if (flag == false) {
      outputArray.push(array[j]);
     }
     flag = false;
}
// tArray = [100, 23, 67, 45]

老手

let array = [100, 23, 23, 23, 23, 67, 45]; 
let outputArray = Array.from(new Set(array))

6. 数组到对象

新手

let arr = ["value1", "value2", "value3"]; 
let arrObject = {};
for (let i = 0; i < arr.length; ++i) {
   if (arr[i] !== undefined) {
     arrObject[i] = arr[i];
   }
}

老手

let arr = ["value1", "value2", "value3"]; 
let arrObject = {...arr}; 

7.对象到数组

新手

let number = {
  one: 1, 
  two: 2,
};
let keys = []; 
for (let numbers in numbers) {
  if (number.hasOwnProperty(number)) {
     keys.push(number);
    }
}
// key = [ 'one', 'two' ]

老手

let number = {
  one: 1, 
  two: 2,
};
let key = Object.keys(numbers); // key = [ 'one', 'two' ]
let value = Object.values(numbers);  // value = [ 1, 2 ]
let entry = Object.entries(numbers); // entry = [['one' : 1], ['two' : 2]]

8. 短路条件

新手

if (docs) {
    goToDocs();
}

老手

docs && goToDocs()

9. 使用^检查数字是否相等

if(a!=123) // before // 一般开发者

if(a^123) // after // B格比较高的

10.对象遍历

const age = {
   Rahul: 20,  
   max: 16
};

// 方案1：先得 key 在遍历 key
const keys = Object.keys(age); 
keys.forEach(key => age[key]++);

console.log(age); // { Rahul: 21, max: 16 }

// 方案2 - `for...in` 循环
for(let key in age){
   age[key]++;
}

console.log(age); // { Rahul: 22, max: 18 }

11. 获取对象的所有键